GUID获取16位19位22位的唯一字符串

/// <summary>

    /// 根据guid获取16位的唯一字符串

    /// </summary>

    /// <param name=\"guid\"></param>

    /// <returns></returns>

    public static string guidto16string()

    {

        long i = 1;

        foreach (byte b in guid.newguid().tobytearray())

            i *= ((int)b + 1);

        return string.format("{0:x}", i - datetime.now.ticks);

    }

    /// <summary>

    /// 根据guid获取19位的唯一数字序列

    /// </summary>

    /// <returns></returns>

    public static long guidtolongid()

    {

        byte[] buffer = guid.newguid().tobytearray();

        return bitconverter.toint64(buffer, 0);

    }

/// <summary>

    /// 生成22位唯一的数字 并发可用

    /// </summary>

    /// <returns></returns>

    public static string generateuniqueid()

    {

        system.threading.thread.sleep(1); //保证yyyymmddhhmmssffff唯一

        random d = new random(bitconverter.toint32(guid.newguid().tobytearray(), 0));

        string strunique = datetime.now.tostring("yyyymmddhhmmssffff") + d.next(1000, 9999);

        return strunique;

    }